Coupling mechanisms are commonly used to join pipe sections, motor housings or the like. Desirable characteristics and features of such mechanisms, often found lacking in prior work in this field, include low manufactured cost, mechanically secure coupling and ease of assembly and disassembly. Other desirable features include a minimal number of parts, a degree of "forgiveness" with respect to variations in certain manufacturing tolerances and the ability to couple structures of equal or disparate sizes.
One type of coupling mechanism is shown in U.S. Pat. No. 198,508 and includes a pipe section with an integral collar and a mating flange with a collar and a pair of rotatable turnbuckles mounted on the collar. When the flange and the mating pipe section are coupled together, the eccentric turnbuckle heads engage the pipe collar. A disadvantage of this arrangement is that the pipe section must have a collar affixed thereto and this adds to manufactured cost. Another, more serious disadvantage is that the eccentric heads can engage the pipe collar in only one position for each 360.degree. rotation of the turnbuckle. Unless machining tolerances are very tightly controlled, the eccentric heads will only loosely engage the pipe collar. Even if such tolerances are exceptionally well controlled, there is no tolerance "forgiveness" as wear occurs on the heads and/or the collar engaged by them.
Another type of coupling mechanism is shown in U.S. Pat. No. 2,867,454. The pipe coupling shown therein is used to join two sections of pipe of equal diameter and equal wall thickness and uses a plurality of keys, each of which engages a notch in the pipe wall. While the coupling shown therein undoubtedly has great mechanical strength, it requires two hubs and two flanges (together with bolts and keys) to achieve secure coupling. Such multiplicity of parts adds to manufactured cost and complexity. In addition, the securing nuts and other component parts must be entirely removed in order to disassemble the coupling.
Yet another form of coupling mechanism is shown in U.S Pat. No. 3,797,949. The described device uses a bolted key and notch for securing a pin within a machine structure. While the mechanism shown therein does not clamp the illustrated parts together in abutting relationship (and in fact is incapable of doing so), it does secure them to prevent relative movement. In addition, the bolt must be entirely removed in order to fully separate the two parts.
Another known type of coupling assembly is found on certain types of motor-driven water pumps. In such units, the electric motor typically has a generally cylindrical housing with either a square or round "bell housing" or flared mounting flange of enlarged dimension. Bolts or other fasteners are used to couple this flange to a mating pad on the pump housing. The inclusion of the flange on the motor housing adds significantly to the housing cost. In addition, such units can be separated (for motor or pump servicing, for example), only by completely removing all of the bolts which couple the pump housing and the motor housing to one another.
A housing coupling mechanism which permits simplification of housing configuration, which permits quick disassembly of the coupled units without the necessity of complete bolt removal, which is "forgiving" of certain dimensional variations and which has a reduced manufactured cost would be an important advance in the art.